Process for graft polymerization of polymerizable monomers to polyethylene terephthalate in presence of a carbon or silicon halide

ABSTRACT

Graft polymerization of a polymerizable monomer to polyethylene terephthalate or to a polyester polymer consisting mainly of polyethylene terephthalate is carried out in the presence of a halide of the general formula MnX2n 2 WHEREIN M is carbon or silicon, X is halogen and n is a positive integer.

United States Patent Sakurada et al.

[451 Mar. 2%, 1972 Japan Atomic Energy Research Institute, Tokyo, JapanFiled: Mar. 17, 1969 Appl No.: 807,938

Assignee:

[30] Foreign Application Priority Data Mar. 19, 1968 Japan ..43/l7842US. Cl. ..204/159.l5, 8/DIG. 12, 8/DIG. l8, 260/33.8 R, 260/873 Int. Cl...C08g 39/10, C08g 51/30, B0 lj l/l0 Field of Search ..260/873, 33.8 R;204/159.15; 8/D1G. 18; 81/1155 References Cited UNITED STATES PATENTSlvl agat et a1.

3,131,138 4/1964 Durup et al. ..8/D1G. 18

3,281,263 10/1966 Priesing et a1. ..204/1 59. 15

3,405,087 10/1968 Fryd ..260/873 3,424,820 l/1969 Magat et al. 260/8733,482,926 12/1969 Cappuccio..... 81/115 5 OTHER PUBLICATIONS Chem.Abstracts, Vol. 70, 1969, 116147C, Radiationlnduced Graft-Polyesters,Okada et al.

Primary Examiner-William H. Short Assistant Examiner-Edward WoodberryAttorney-Totem & McGeady ABSTRACT Graft polymerization of apolymerizable monomer to I polyethylene terephthalate or to a polyesterpolymer consisting mainly of polyethylene terephthalate is carried outin the presence of a halide of the general formula wherein M is carbonor silicon, X is halogen and n is a positive integer.

14 Claims, No Drawings SUMMARY OF THE INVENTION This invention generallyrelates to graft polymerization and is particularly directed to animproved process for graft polymerizing a polymerizable organic monomerto a polyester polymer.

Polyester polymers, as for example polyethylene terephthalate with whichthe invention is primarily concerned, are high molecular weightcompounds that are widely used in the manufacture of synthetic fibers,films and the like fabricated articles. Such polymers exhibit, however,certain disadvantageous properties which negatively afiect theirusefulness. They are thus hygroscopic and take dyes with difficultyonly. Further, they are readily charged electrostatically, therebyattracting dust particles which have a tendency to adhere and deposit onthe polymer surfaces and are difficult to be removed therefrom. Theadhesive properties of these polymers to rubber are also extremely poor.

With a view to overcoming these disadvantages, it has previously beenattempted to graft a suitable polymerizable monomer to the polyester.Various graft polymerization procedures have been proposed for thispurpose. For example, it has been suggested that the grafting of thepolymerizable monomer to the polyester be effected while irradiating thepolyester with high energy ionizing rays in the presence of a swellingagent for the polyester. A number of swelling agents have been proposedfor this purpose, for example, organic acids such as formic acid oracetic acid, inorganic acids, such as sulfuric acid, alcohols, such asmethanol or ethanol and the like. According to a different method, graftpolymerization is effected in the presence of a polymerization initiatorsuch as, for example, benzoyl peroxide or azobisisobutyronitrile. Theseprior art methods, however, are unsatisfactory to the extent that theyield, to wit, the grafting percentage is low. In addition, thesemethods are relatively cumbersome to carry out.

Accordingly, it is a primary object of the present invention to providea process for graft polymerizing a polymerizable monomer to a polyesterwhich overcomes the disadvantages of the prior art procedures and whichresults in a grafted product of high grafting percentage.

Another object of the present invention is to provide a process of theindicated kind in which the formation of polymers other than the desiredgraft polymer is effectively suppressed.

Still another object of the present invention is to provide a processfor graft polymerizing a polymerizable monomer to fibrous polyesterwithout degrading or negatively afi'ecting the properties of the fibers.

It is also an object of the present invention to provide a process ofthe indicated kind wherein the final product has superior opening andseparating properties, can be readily dyed and has superior thermal,mechanical and chemical characteristics.

Generally, it is an object of the present invention to improve on theart of graft polymerization as presently practiced.

Briefly, and in accordance with this invention, the above objects aresuperiorly obtained by carrying out the graft polymerization in thepresence of a halide represented by the general formula Malian;

wherein M represents carbon or silicon, X is halogen and n is a positiveinteger.

The polymerizable monomer should be iififidfiihiii 11;

ture and is advantageously applied to the system in the form of anaqueous solution or dispersion. A wide variety of polymerizable monomersmay be used for the inventive purposes such as, for example,polymerizable organic bases, organic acids and organic acid salts.

In essence, therefore, the invention provides for a process wherein ahydrophilic monomer, such as a polymerizable organic base, organic acidor organic acid salt, is grafted to a polyester in the presence of theindicated halide.

The inventive procedure is preferably carried out by first impregnatingthe polyester with the halide, which is a fully halogenated compound,such as, for example, carbon tetrachloride, hexachloroethane, carbontetrabromide or silicon tetrachloride. Due to the impregnation of thepolyester with the halide, a certain percentage of halide isincorporated within the polyester structure and, after admixture withthe monomer, the graft polymerization is then conducted. The graftingreaction proceeds smoothly and no grafting initiator is generallyrequired.

It is an important feature of the present invention that the beneficialeffects are dependent on the use of a fully halogenated compound.Experiments have thus indicated that halogenated hydrocarbons which arenot fully halogenated,

.such as, for example, chloroform, ethylene dichloride andtrichloroethylene, do not yield satisfactory results. Further,

the use of prior art swelling agents for polyesters, such as benzene anddimethylformamide, does not result in comparable grafting efiects. As amatter of fact, the grafting percentage obtained with the use ofswelling agents or incompletely halogenated hydrocarbons is essentiallyzero. While applicants do not wish to be limited by any theoriesadvanced by them, it is believed that the fully or completelyhalogenated compound in whose presence the inventive grafting reactionis carried out, acts not only as a swelling agent for the polyester butalso forms a complex with the polyester, which complex in turn reactswith the monomer to form a radical or radicals to .initiats tis srsftnym as s Bayesian? 1:

As previously stated, the halide in whose presence the inventivereaction is carried out is indicated by the general formula M x whereinM is carbon or silicon, X is halogen, and n is a positive integer. Thesehalides are thus either completely halogenated hydrocarbons, such ascarbon tetrachloride, carbon tetrabromide and hexachloroethane, or arecompletely halogenated silicones, such as silicon tetrachloride.

It has been ascertained that a certain minimum amount of halide has tobe incorporated within the polyester structure in order to initiate andsuccessfully carry out the grafting reaction. Is has thus been foundthat at least 0.3 percent by weight of halide, calculated on the amountof polyester, has to be present to obtain satisfactory results. Forexample, when carbon tetrachloride is employed as the halide, 0.3-25percent by weight of carbon tetrachloride, calculated on the weight ofthe polyester, gives the best result.

The halide may be supplied to the reaction in different ways. Accordingto one embodiment, and if the halide is a liquid, such as for examplecarbon tetrachloride, the polyester is advantageously immersed in theliquid halide, whereby the halide becomes incorporated into thepolyester. However, if the halide is a solid, such as, for example,carbon tetrabromide or hexachloroethane, the solid halide may first bedissolved in a solvent such as benzene, and the polyester is thenimmersed in the solution. The immersion of the polyester in the halidemay be advantageously effected at temperatures above room temperature. in 0 7 H Assuming that the halide is carbon tetrachloride and thepolyester is in the form of non-stretched non-crystalline polyethyleneterephthalate fibers, the principal concepts of the invention may bebriefly summarized as follows:

The polyester fibers are impregnated so as to incorporate therein atleast 0.3 percent by weight of carbon tetrachloride, to wit, the minimumamount necessary for successfully carrying out the inventive process.The impregnation may be performed by immersing the polyester fibers inthe carbon tetrachloride at room temperature or at elevatedtemperatures. After the immersion, the fibers are withdrawn from theimmersion bath. If the polyester fibers are immersed in the carbontetrachloride liquid for, say, 30 minutes, the amount of liquidincorporated in the polyester is 0.8 percent if the immersion took placeat 30 C. The corresponding amount is 5.4 percent if the impregnationtook place at 35 C. and 18 percent at immersion temperatures in excessof 40 C. For incorporating about 4 percent of carbon tetrachloride inthe polyester, the immersion of the polyester in the liquid should lastfor about 5 minutes at 40 C., 2.5 minutes at 50 C. and 1 minute at 55 C.It will thus be appreciated that the temperature of the immersion bathis a factor in respect to the amount of halide to be incorporated, theamount of incorporation also being dependent on the immersion time.

However, in case crystalline polyester fibers are to be treated whichhave been obtained by stretching and by subjecting non-crystallinefibers to heat treatment, the polyester fibers may then be immersed in amixture of carbon tetrachloride and chloroform or dimethylformamide, thelatter being a good swelling agent for polyesters. The mixing ratio ofthe carbon tetrachloride on the one hand and the chloroform ordimethylformamide on the other hand should preferably be about 1:1. Byusing such a mixture, the polyester can be treated essentially in thesame manner as in the treatment of non-stretched polyester. For example,by treating the polyester with the indicated mixed liquid system at atemperature in excess of 60 C. but lower than the boiling point of themixture, the amount of liquid incorporated in the polyester can beincreased to 20-32 percent. Further, with a view to obtaining a similareffect, non-stretched polyester fibers may be immersed first in carbontetrachloride as described above, whereupon the thus impregnated fibersare stretched in a conventional manner.

The polyester in whose structure the completely halogenated compound hasbeen incorporated is then caused to react with an aqueous solution ordispersion of the polymerizable monomer which, as previously stated, maybe a polymerizable organic base, organic acid or an organic acid salt.

A large variety of such polymerizable monomers may be used. Thefollowing examples are illustrative of suitable polymerizable monomers.

Organic base such as 4-vinylpyridine and 2-vinyl-pyridine; organic acidsuch as acrylic acid, methacrylic acid, maleic anhydride, itaconic acid,vinylsulfonic acid, and styrene sulfonic acid; organic acid salt such asa sodium salt of the aforesaid organic acids.

Monomers exhibiting low water solubility are most profitably used in theform of aqueous dispersions. For this purpose, it is advantageous toprepare an emulsion of the respective monomer. The emulsions areadvantageously prepared with the aid of a nonionic surface active agentsuch as polyoxyethylene sorbitan monolaurate and sorbitan laurate or acationic surface active agent such as stearyltrimethyl ammonium chlorideand cetylpyridinium chloride in an amount of 0. l-l .0 percent byweight. However, is is perfectly feasible to use the monomers in theform of aqueous solutions. The concentration of the monomer and otheradditives, such as non-polymerizable acid, as mentioned below, isadvantageously in the range of l-20 percent by weight.

The grafting reaction is advantageously conducted at a temperature offrom room temperature to about 100 C. However, the reaction temperatureis not really critical and and the inventive process therefore is notlimited to a particular temperature range.

The reaction may be effectively conducted in the presence of air.However, it is preferred to perform the grafting reaction either invacuo or in an inert gas atmosphere such as a nitrogen atmosphere,whereby the reaction period for obtaining the desired graftingpercentage may be materially reduced. Further, the grafting reaction maybe promoted by irradiation. Ionizing high energy rays are thus effectivefor facilitating the reaction. On the other hand, the addition of knownprior art polymerization initiators is not particularly effective forthe purposes of increasing the grafting percentage.

The invention encompasses not only the use of a single polymerizablemonomer to be grafted to the polyester, but mixtures of severalpolymerizable monomers may also be used. When a combination of monomersis used as, for example, a combination of a polymerizable base and apolymerizable organic acid or an organic acid salt, the graftingreaction can be further promoted and at the same time undesired sidepolymerization reactions for the formation of non-graft polymers can beeffectively suppressed.

There are no particular limitations in respect to the combination ofpolymerizable monomers and any suitable combination may be selected inaccordance with the kind of monomers to be employed. However, in casewhere a polymerizable organic base such as 4-vinylpyridine isgraftpolymerized to polyester, it is preferable to add 3-20 parts ofpolymerizable organic acid to -97 parts of the polymerizable organicbase and also in case where a polymerizable organic acid such as acrylicacid is graft-polymerized to polyester, it is preferable to incorporate5-30 parts of polymerizable organic base to 70-95 parts of the organicacid. By selecting the above combination of monomers, the formation ofother polymers than graft polymer can be very remarkably suppressed.

In addition, the effects of promoting the graft polymerization andsuppressing the formation of non-graft polymers can also be obtained byadding a small proportion of such nonpolymerizable organic acids asoxalic acid, formic acid, acetic acid, propionic acid and benzoic acidor an inorganic acid such as sulfuric acid, hydrochloric acid, nitricacid, phosphoric acid and boric acid, to the polymerizable organic baseor by adding pyridine to the polymerizable organic acid. Furthermore,when the grafting reaction is conducted while adding a small proportionof an acid to the polymerizable organic base, the pH of thepolymerization system is adjusted to about 7, whereby the grafting canbe achieved without causing the degradation of the polyesters and fibersprepared from the polymer. In other words, in the process of thisinvention, when the polymerizable organic base or the polymerizableorganic acid is used alone as the monomer to be grafted to polyester,the pH of the polymerization system is strikingly increased in thefonner case and considerably decreased in the latter case. Accordingly,in both cases, the polyester fibers thus treated might thus be degradedduring the graft polymerization. This is avoided by using a combinationof polymerizable organic base and polymerizable organic acid, acombination of polymerizable organic base and a non-polymerizableorganic acid, or a combination of polymerizable organic acid andnonpolymerizable organic base. The pH of the polymerization system canthus be controlled besides the suppression of the occurrence of thenon-grafting reaction, as mentioned above, and hence the degradation offibers is effectively prevented.

The invention also encompasses that the monomer to be graft-polymerizedto polyester can be graft-polymerized together with a vinyl monomer suchas acrylonitrile, styrene, methyl methacrylate, ethyl methacrylate,propyl methacrylate, butyl methacrylate, methyl acrylate, ethylacrylate, propyl acrylate, butyl acrylate and vinyl acetate. This mannerof operation is very effective from a practical point of view. The kindof monomers capable of being graft-polymerized to polyester can thus beextended to include inexpensive and easily available vinyl monomers andhence the process is very economical. For example, since 4-vinylpyridineor acrylic acid can be graft-copolymerized to polyester together withacrylonitrile, polyester fibers having a high fastness and good dyeingproperty and heat resistance can be readily obtained.

Furthermore, since 4-vinylpyridine and styrene can be graftcopolymerizedto polyester, polyesters having an excellent moldability andfabricability can be obtained.

The process of this invention is very effective for graftpolymerizingpolymerizable organic base, polymerizable organic acid or organic acidsalt to polyester. For example, usual polyethylene terephthalate fibersare not dyed by Brilliant Scarlet 3R or Crystal Violet or are onlyfaintly dyed by Kayalon Fast Brown, which is a dispersed dye. Bycontrast, when 4-vinylpyridine is graft-copolymerized to polyethyleneterephthalate fibers together with a polymerizable organic acid such asacrylic acid, the grafted polyethylene terephthalate fibers are dyeddeeply by these dyes as in wool. Furthermore, the polyester fibersprocessed by the process of this invention exhibit strikingly improvedhygroscopic and antistatic properties.

The process of this invention will now be explained by the followingexamples, although the invention shall not be limited to them, percentin all instances being percent by weight.

The invention will now be described by several examples it beingunderstood, however, that these examples are given by way ofillustrations and not by way of limitations and that many changes may beeffected without effecting the scope and spirit of the invention asrecited in the appended claims.

EXAMPLE 1 After washing in cold water for 24 hours and drying at roomtemperature under reduced pressure, about 100 mg. of unstretchedpolyester fibers (yarn which consist of 18 monofilaments each havingdeniers) were immersed in carbon tetrachloride for 1 hour at 50 C. andthen air-dried for 1 hour at room temperature. By measuring the weightof the fibers, it was ascertained that the fibers contained 16.1 percentof carbon tetrachloride.

The fibers were inserted into a test tube having an outerdiameter of 1cm. 10 ml. of an aqueous emulsion (pl-18.8) of 10 percent4-vinylpyridine and 0.5 percent of an emulsifier known as Nissan nonionLT-22l (trade name of Nissan Chemical Industry Co. for polyoxyethylenesorbitan monolaurate) was poured in the test tube. After purging the airin the test tube with nitrogen, the test tube was sealed. After heatingthe system for 2 hours at 50 C., the fibers were withdrawn from the testtube, washed with water for 16 hours at 50 C., and washed with ethanolfor 16 hours at 50 C. to remove nongrafted polymers. The fibers wereweighed after drying them at 50 C. in a vacuum oven to ascertain thepercentage of weight increase (grafting percentage) which was 21.0percent.

For comparison purposes, the same graft polymerization procedure wascarried out under the same conditions except that no pretreatment withcarbon tetrachloride was effected. The percentage of weight increase wasthen only 1.0 percent.

EXAMPLE 2 The same procedure as in Example 1 was carried out but usingan aqueous emulsion (pH 7.2) prepared by adding 0.1 ml. of acrylic acidto 10 ml. of the aforesaid emulsion of 10 percent 4-vinylpyridine and0.5 percent emulsifier. The grafting percentage in this experiment was31.1 percent. The grafting percentage was thus higher than that inExample 1. Further, the formation of undesirable polymer other than thegraft polymer was effectively suppressed and the opening property of thegrafted fibers was improved. In addition, when the grafted fibers thusobtained were stretched to five times their original length in hot waterof 80 C., the strength of the fibers was 3.45 g./denier.

For comparison purposes and without pretreating the polyester fibers incarbon tetrachloride, the polyester fibers were immersed in an aqueousemulsion of 10 percent 4-vinylpyridine and 0.5 percent of the emulsifierand then irradiated by gamma rays of 1.1 10' roentgens/hr. for 4 hoursat 50 C. In this case, the grafting percentage was 30.2 percent. Whenthe grafted fibers were stretched to five times their original lengthunder the same conditions as described above, the strength thereof was3.02 gjdenier.

EXAMPLE 3 TABLE 1 Amount of acrylic Grafting percentage acid (ml.)' pHCCl content 15-46% No CC],

The amount of acrylic acid added to 10 ml. of an emulsion of 10%4-vinylpyridine.

The above results confirm that the incorporation of carbon tetrachlorideis a decisive factor for obtaining an increase of the graftingpercentage.

In addition, it was found that by adding acrylic acid, the formation ofnon-graft polymers was effectively suppressed and the opening propertyof the grafted fibers was improved.

EXAMPLE 4 After washing with cold water for 24 hours and drying at roomtemperature under reduced pressure, about 100 mg. of unstretchedpolyester fibers (yarn of 70 filaments each having 5.5. deniers) wereimmersed in carbon tetrachloride for 1 hour at 50 and dried for 30minutes at room temperature under reduced pressure. By weighing thefibers, it was confirmed that the fibers contained about 18 percent ofcarbon tetrachloride.

The fibers were thereafter immersed in 5 ml. of an aqueous emulsion (pH7.0) of 10 parts of 4-vinylpyridine, 1 part of methacrylic acid, partsof water and 0.5 part of the aforesaid emulsifier in a test tube. Afterpassing nitrogen through the test tube for 2 minutes, the tube wassealed. After heating for 2 hours at 50 C., the grafting percentage was31.3 percent.

When the fibers were irradiated by gamma rays of the same dosage as inExample 3 at 50 C., the grafting percentage was 32.2 percent. On theother hand, for comparison, when the same procedure as above was appliedto polyester fibers which had not been immersed in carbon tetrachloride,the grafting percentage was only 0.6 percentage and even if theirradiation of gamma rays was perfonned, the grafting percentage wasonly 9.0 percent.

EXAMPLE 5 Polyester fibers as in Example 1 were immersed in carbontetrachloride for 20 hours at 40 C. After withdrawal of the fibers anddrying for 5 minutes in air, the fibers contained 18.2 percent of carbontetrachloride. The fibers (about 200 mg.) were then placed in a testtube having a diameter of 1 cm. and 6 ml. of a 5 percent aqueoussolution (pH 6.8) of sodium styrenesulfonate containing 2.5 percent of asurface active agent were added to the test tube. After purging the airin the test tube with nitrogen and sealing the tube, the system wasreacted for 3 hours at 60 C. After termination of the reaction, thehomopolymer formed was extracted with water and the grafting percentageof sodium styrenesulfonate was ascertained to be 10.5 percent.

The same procedure as above was carried out using styrenesulfonic acid(pH 6.2) instead of sodium styrenesulfonate. After completion of thereaction, the homopolymer thus formed was extracted with diluted aqueousammonia and water. The grafting percentage of styrenesulfonic acid was9.5 percent.

EXAMPLE 6 A sample containing 17.4 percent of carbon tetrachloride wasprepared by treating 100 mg. of polyester fibers of Example 1 accordingto the same procedure as described in Example l. The yarn was placed ina test tube and ml. of a mixture (pH 3.4) of parts of acrylic acid, 2parts of 2-vinylpyridine, 0.5 parts of the emulsifier as in Example 1,and 90 parts of water was added to the test tube. After purging the airin the test tube with nitrogen for 2 minutes and sealing the tube, thesystem was reacted for 2 hours at 50 C. The fibers were thereafterwithdrawn from the test tube, washed with water for 16 hours at 50 C.and further washed with ethanol for 16 hours at 50 C. to removenon-grafted polymers. The grafting percentage of the grafted fibers was3.5 percent. When irradiation of 1.1 X 10 roentgens/hr. of gamma rayswas applied to the fibers during the reaction, the grafting percentagewas 6.3 percent.

EXAMPLE 7 By treating l00 mg. of polyester fibers as in Example 4according to the procedure of Example 1, 18.2 percent carbontetrachloride was added to the fibers. The fibers were placed in a testtube having an outer diameter of 1 cm. 5 ml. of a mixture (pH 4.2) of6parts of acrylic acid, 4 parts of pyridine, 0.5 parts of the emulsifierof Example 1, and 90 parts of water was added to the test tube. Afterpurging the air in the test tube with nitrogen and sealing it, thesystem was heated for 2 hours at 50 C. and the yarn was processed as inExample 6. The grafting percentage of the grafted fibers was 2.0percent.

When irradiation with gamma rays was carried out as in Example 6, thegrafting percentage was 8.9 percent On the other hand, when theirradiation with gamma rays was conducted without previouslyimpregnating the fibers with carbon tetrachloride, the graftingpercentage of the grafted fibers was only 0.3 percent.

EXAMPLE 8 The polyester fibers of Example 1 were impregnated with about18 percent of carbon tetrachloride by the same procedure as in the aboveexample and the fibers and a 5 percent aqueous solution of4-vinylpyridine and sodium styrenesulfonate in an amount of 30 times theweight of the fibers were heated at 60 C. for 3 hours in a nitrogenatmosphere. Thereafter, the fibers were washed with ethanol and thegrafting percentage was measured, the results of which are shown in thefollowing Table 2 together with the it EXAMPLE 9 The polyester fibers asin Example 1 were impregnated with about 18 percent of carbontetrachloride by the same procedure as in the above-mentioned example.The fibers were subjected to graft polymerization for 6 hours at 60 C.with the addition of a 10 percent aqueous solution of 4 vinylpyridineand a non-polymerizable organic acid such as acetic acid or oxalic acidor an inorganic acid such as sulfuric acid or hydrochloric acid. Afterwashing the fibers with ethanol, the grafting percentage of the graftedfibers was measured. The results are shown in the following Table 3.

TABLE 3 Mixing ration in weight Non-polymerizable pH of Grafting4-Vinylpyridine acid liquid percentage 9 acetic acid 1 6.6 6.0

B acetic acid 2 6.2 9.0

9 oxalic acid 1 7.2 73.6

7 oxalic acid 3 6.0 7.0

9 sulfuric acid 1 6.6 33.0

7 sulfuric acid 3 4.5 7.3

9 hydrochloric acid I 6.0 48.8 7 hydrochloric acid 3 2.0 7.4

EXAMPLE 10 The same grafting procedure as in Example 8 was carried out,using a mixture of 4-vinylpyridine and acrylonitrile instead of amixture of 4-vinylpyridine and sodium styrene-sulfonate. After non-graftpolymers were removed from the fibers by washing with ethanol, a graftpolymer having a high grafting percentage as shown in Table 4 wasobtained. On the other hand, when only acrylonitrile was used in thesame The polyester fibers as in Example 1 were immersed in carbontetrachloride for 3 hours at room temperature, withdrawn, wiped lightlywith filter paper, and allowed to stand for 5 minutes in open air. Thefibers contained 8.9 percent of carbon tetrachloride. The fibers werethen heated for 3 hours to 60 C. in a nitrogen atmosphere together witha liquid (pl-l 6.8) having a composition of 9 parts of 4-vinylpyridine,1 part of methacrylic acid, 0.5 part of a surface active agent, and 89.5parts of water, in an amount of about 30 times the weight of the fibers.The heating was carried out in a sealed tube and after removingnon-graft polymers from the fibers by washing with ethanol, the graftingpercentage of the grafted fibers was measured. The ascertained value was42.4 percent.

In addition, for comparison, the same procedure was conducted withoutthe treatment with carbon tetrachloride. The grafting percentage wasthen less than 1 percent.

, 9 EXAMPLE 12 The same procedure as in Example 1 l was carried outwhile omitting the pretreatment with carbon tetrachloride as in theaforesaid comparative experiment, but adding instead parts of carbontetrachloride to the reaction mixture of the graft polymerization. Thegrafting percentage of the fibers was 28.2 percent.

EXAMPLE 13 By conducting the treatment with carbon tetrachloride at roomtemperature as in Example 11, polyester fibers containing 3 percent ofcarbon tetrachloride were prepared. The fibers were heated at 60 C. for6 hours in the presence of air together with a liquid (pH 7.0) havingthe same composition as in Example 1 1, except that acrylic acid wasused instead of methacrylic acid. The grafting percentage of the graftedfibers was 7.6 percent.

EXAMPLE 14 Commercially available polyester fibers were treated for 1hour at the temperature shown in Table 5 with a binary liquid systemmixture consisting of 50 parts of carbon tetrachloride and 50 parts of aswelling agent for polyester, such as, chloroform, ethylene dichlorideor dimethyl formamide. The fibers were withdrawn, wiped with filterpaper, and immediately weighed. The amount of the liquid incorporated inthe fibers is shown in Table 5.

The fibers were then heated in a select tube for 6 hours at 60 C. in anitrogen atmosphere together with a liquid (pl-l 7.0) consisting of 9parts of 4-vinylpyridine, 1 part of acrylic acid, 0.5 part of surfaceactive agent and 89.5 parts of water in an amount of about 30 times theweight of the fibers. After removing non-graft polymers by washing thefibers with ethanol, the grafting percentage was measured. The value wasabove 18.2 percent in each case as shown in the same table.

In addition, for comparison, the same procedure as above was conductedusing chloroform, ethylene dichloride or dimethyl formamide alonewithout adding carbon tetrachloride. The grafting percentage was thenless than 3.3 percent.

A piece of polyethylene terephthalate film having a thickness of 0.1 mm.was washed with water, dried, and then immersed in a mixture of 50 partsof carbon tetrachloride and 50 parts of chloroform to incorporate 18.2percent of the liquid in the film by the procedure described in Example14. The graft polymerization was thereafter carried out under the sameconditions as in Example 14. The grafting percentage of the grafted filmwas 6.4 percent.

EXAMPLE 16 The polyethylene terephthalate fibers as in Example 1 werewashed with cold water for 24 hours and dried at room temperature underreduced pressure. About 100 mg. of the fibers were then immersed in amixture of 10 parts of carbon tetrabromide and parts of benzene for 16hours at 50 C. When the fibers were air-dried for 5.5 hours at roomtemperature and then weighed it was confirmed that the weight of thefibers had increased by 12.0 percent due to incorporation of the mixtureof carbon tetrabromide and benzene.

The fibers were then placed in a test tube having an outer diameter of 1cm. A mixture of 9 parts of 4-vinylpyridine, 1 part of acrylic acid, 0.5part of the emulsifier and 90 parts of water was added to the tube, asin Example 1. After purging the air in the test tube with nitrogen gasfor 2 minutes and sealing the same, the system was heated at 50 C. for 2hours and non-graft polymers were removed from the grafted fibers by thesame manner as in Example 1. Polyethylene terephthalate fibers to which26.5 percent of the mixture of 4-vinylpyridine and acrylic acid had beengrafted were thus obtained.

EXAMPLE l7 Polyethylene terephthalate fibers containing a mixture ofcarbon tetrabromide and benzene were prepared by the same procedureas inExample 16. The fibers were placed in a test tube having an outerdiameter of 1 cm. A mixture of 9 parts of 4-vinylpyridine, 1 part ofacrylic acid, 0.5 part of the emulsifier and 90 parts of water was addedto the test tube as in Exam ple l. The tube was sealed after passingnitrogen gas through the test tube for 2 minutes to purge the air. Thesystem was then irradiated by gamma rays of 1.1 X 10 roentgens/hr underheating at 50 C. The fibers were then withdrawn, non-graft polymers wereremoved therefrom in the same manner as in Example 1 and the graftingpercentage of the fibers was measured. The value was 45.2 percent.

In addition, for comparison, polyethylene terephthalate fibers werepretreated with benzene only to incorporate 4.5 percent of benzene inthe fibers in a manner similar as above. The system was irradiated bygamma rays for 6 hours under heating at 50 C. The grafting percentagewas only 20.6 percent.

EXAMPLE 18 The polyethylene terephthalate as in Example 1 was washedwith cold water for 24 hours and dried at room temperature under reducedpressure. About mg. of the fibers were immersed in silicon tetrachloridefor 16 hours at 50 C., withdrawn, air-dried for 30 minutes at roomtemperature, and weighed. It was ascertained that the fibers containedsilicon tetrachloride in an amount of 3.1 percent of the weight of thefibers. The fibers were then placed in a test tube of 1 cm diameter andan aqueous emulsion of 4-vinylpyridine and acrylic acid having the samecomposition as in Example 4 was added to the tube. After purging the airin the tube with nitrogen and sealing the tube, the system was heated at50 C. for 2 hours. After removing non-graft polymers in the same manneras in Example 1, the grafting percentage of the fibers thus grafted wasmeasured. The grafting percentage was 7.0 percent.

EXAMPLE 19 The polyethylene terephthalate as in Example 1 was washedwith cold water for 24 hours, and dried at room temperature underreduced pressure. About 100 mg. of the fibers were then immersed in amixture of 10 parts of hexachloroethane and 90 parts of benzene for 18hours at 50 C. The fibers were then withdrawn and weighed, to show aweight increase of 9.2 percent through impregnation or incorporation ofthe mixture. The fibers were placed in a test tube of 1 cm diameter inan aqueous emulsion of 4-vinylpyridine and acrylic acid hav- 5 ing thesame composition as in Example 4. After purging the EXAMPLE 20 The sameprocedure as in Example 19 was carried out, except that the fibers wereirradiated for 2 hours by gamma rays of 1.1 X 10 roentgens/hr. from Counder heating at 50 C. instead of heating them at 50 C. for 2 hours. Thegrafting percentage ofthe fibers was then 79.2 percent.

EXAMPLE 21 The polyester fibers as in Example 1 were washed with coldwater for 20 hours and dried at room temperature under reduced pressure.About 100 mg. of the fibers were then immersed in carbon tetrachloridefor 1 hour at 50 C. After the fibers were air-dried for 1 hour at roomtemperature, it was confirmed that the fibers contained 17.3 percent ofcarbon tetrachloride. The fibers were then stretched to times theirinitial length in water at 80 C. The content of carbon tetrachloride wasthen 5.45 percent.

The fibers were then placed in a test tube having an outer diameter of 1cm. and ml. of a mixture of 10 parts of 4- vinylpyridine, 1 part ofacrylic acid, 90 parts of water and 0.5 part of the emulsifier as inExample 1 was added to the test tube. After purging the air in the testtube with nitrogen for 2 minutes and sealing it, the system was heatedfor 2 hours at 50 C. After withdrawing the fibers, non-graft polymerswere removed therefrom by the same manner as in Example 1. After dryingthe fibers in a vacuum oven at 50 C., the fibers were weighed. Thegrafting percentage was 40.7 percent.

EXAMPLE 22 The polyester fibers as in Example 1 were washed with coldwater for 20 hours, dried at room temperature under reduced pressure andabout 100 mg. of the fibers were immersed in carbon tetrachloride forminutes at 35 C. The fibers were withdrawn and air-dried for 1 hour atnormal room temperature, whereby fibers containing 4.3 percent of carbontetrachloride were obtained.

The fibers were then placed in a test tube having an outer diameter of 1cm. and 5 ml. of a mixture of 10 parts of 2- methyl-5-vinylpyridine, 1part of acrylic acid, 90 parts of water and 0.5 part of the emulsifierof Example 1 was added to the tube. The tube was sufficiently evacuatedby a vacuum line and sealed under vacuum. The system was then heated at50 C. for 2 hours and the fibers were withdrawn therefrom. The fibersthus obtained had a very good opening property and the grafted productcontained almost no non-graft polymers. The grafted fibers were washedwith methanol and the grafting percentage of the fibers was measured,which showed a value of 12.5 percent.

EXAMPLE 23 The polyester fibers as in Example 22 were impregnated with4.3 percent of carbon tetrachloride in the same manner as in saidexample. The fibers were then placed in a test tube having an outerdiameter of 1 cm. and a mixture of 10 parts of 4-vinylpyridine, 1 partof maleic anhydride, 90 parts of water and 0.5 part of the emulsifier ofExample 1 was added to the test tube. After evacuating sufficiently thetest tube by means of a vacuum pump and sealing the test tube undervacuum, the system was heated for 30 minutes at 50 C. and the fiberswere withdrawn therefrom. The grafted fibers thus obtained showed a veryexcellent opening property and contained almost no non-graft polymers.After washing the fibers first with warm water at 50 C. and thenethanol, the grafting percentage of the fibers was measured, the valueof which was 45.8 percent.

r .1 EXAMPLE 24 When the same procedure as in Example 23 was carried outusing itaconic acid instead of maleic anhydride, the grafting percentageof the fibers obtained was 26.4 percent.

EXAMPLE 25 The polyester fibers as in Example 1 were impregnated with5.1 percent of carbon tetrachloride in the same manner as in Example 22.The fibers were placed in a test tube having an outer diameter of 1 cm.and 5 ml. ofa mixture of 10 parts of 4- vinylpyridine, 1 part ofallylsulfonate, parts of water and 0.5 part of the emulsifier of Example1 was added to the test tube. After purging the air in the test tube for2 minutes with nitrogen and sealing the tube, the system was irradiatedby gamma rays of 1.1 X 10 roentgens/hr. for 1 hour under heating at 50C. to provide grafted fibers exhibiting a very good opening property. Inaddition, although the grafted fibers contained almost no non-graftpolymers, they were washed with water of 50 C., and with ethanol at roomtemperature and the grafting percentage of the fibers was measured, thevalue of which was 60.4 percent.

EXAMPLE 26 The same procedure as in Example 25 was carried out usingsodium acrylate instead of allylsulfonate. The grafting percentage ofthe grafted fibers was 39.5 percent.

EXAMPLE 27 The same procedure as in Example 25 was carried out usingpotassium acrylate instead of allylsulfonate. The grafting percentage ofthe fibers thus grafted was 36.6 percent.

EXAMPLE 28 The polyester fibers as in Example 1 were washed with coldwater for 20 hours, dried at room temperature under reduced pressure,and about mg. of the fibers was immersed in carbon tetrachloride for 30minutes at 40 C. The fibers were withdrawn, and air-dried for 1 hour atroom temperature whereby fibers containing 18 percent of carbontetrachloride were obtained.

The fibers were placed in a test tube having an outer diameter of 1 cmand after adding 5 parts of a 4-vinylpyridinestyrene mixture, 0.5 partof emulsifier and 94.5 parts of water, the system was heated at 60 C.for 3 hours to conduct the graft polymerization. By removing non-graftpolymers by washing the fibers with benzene and ethanol, a graft polymerhaving a high grafting percentage as shown in the following Table 6 wasobtained. For comparison, the same procedure as above was conductedwithout employing 4-vinylpyridine. The grafting percentage of the fibersthus obtained was then very low.

TABLE 6 The same grafting reaction as in Example 28 was conducted usinga mixture of 4-vinylpyridine and methyl methacrylate instead of amixture of 4-vinylpyridine and styrene and non-graft polymers wereremoved by acetone and ethanol to obtain grafted fibers having a highgrafting percentage as shown in the following Table 7. On the otherhand, when the same procedure was repeated while using only methylmethacrylate, the grafting percentage of the fibers thus grafted wasvery low.

TABLE 7 Mixing ratio in weight Grafting 4-Vinylpyridine Methylmethacrylate percentage What is claimed is:

1. In a process of graft polymerizing a polymerizable monomer topolyethylene terephthalate, the improvement which comprises that thepolymerizable monomer is of hydrophilic nature and comprises 4-vinylpyridine, 2-vinyl pyridine or Zmethyl-Svinyl pyridine and the graftpolymerization is carried out in the presence of at least 3 percent byweight, calculated on the amount of polyethylene terephthalate of ahalide of the formula M,,X wherein M is carbon or silicon, X is C1 or Brand n is l or 2.

2. The improvement as claimed in claim 1, wherein said polymerizablemonomer also comprises a polymerizable unsaturated organic acid or itssodium salt.

3. The improvement as claimed in claim 1, wherein the process is carriedout by first immersing the polyethylene terephthalate in said halide ora solution thereof to incorporate between about 0.3-25 percent of saidhalide within the polyethylene terephthalate structure, whereafter thegrafting reaction in the presence of said monomer is performed.

4. The improvement as claimed in claim 1, wherein said 'polymerizablemonomer, in addition to said 4-vinyl pyridine,

2-vinyl pyridine or 2-methyl-5-vinyl pyridine, contains a memberselected from the group consisting of acrylic acid, methacrylic acid,maleic anhydride, itaconic acid, vinyl-sulfonic acid, allylsulfonicacid, styrene sulfonic acid and the sodium salts of these organic acids.

5. The improvement as claimed in claim 1, wherein said halide isselected from the group consisting of carbon tetrachloride, carbontetrabromide, hexachloroethane and silicon tetrachloride.

6. A process for the graft polymerization of polyethylene terephthalate,which comprises immersing the polyethylene terephthalate in a solutionof a halide represented by the general formula M x wherein M is carbonor silicon, X is Cl or Br and n is 1 or 2, to incorporate between about0.3-25 percent by weight of said halide into the polyethyleneterephthalate structure and then reacting the halide enrichedpolyethylene terephthalate with at least one hydrophilic polymerizablemonomer selected from the group consisting of 4-vinyl pyridine, 2-vinylpyridine and 2-methyl-5-vinyl pyridine.

7. A process as claimed in claim 6, wherein said reaction between saidmonomer and said halide enriched polyethylene terephthalate is carriedout in a temperature range of from room temperature to C.

8. A process as claimed in claim 6, wherein said 2 vinyl pyridine,4-vinyl pyridine or 2-methyl-5-vinyl pyridine monomer also contains amember of the group consisting of acrylic acid, methacrylic acid, maleicanhydride, itaconic acid, vinylsulfonic acid, allylsulfonic acid,styrene sulfonic acid and the sodium salt of these organic acids.

9. A process as claimed in claim 6, wherein said halide is carbontetrachloride, carbon tetrabromide, hexachloroethane orsilicontetrachloride.

0. A process as claimed in claim 6, wherein the graft polymerizationreaction between said monomer and said halide enriched polyethyleneterephthalate is carried out under irradiation of high energy ionizingrays.

11. A process as claimed in claim 6, wherein the grafting reactionbetween said polymerizable monomer and said halide enriched polyethyleneterephthalate is carried out in the additional presence of a vinylmonomer selected from the group consisting of acrylonitrile, styrene,methyl methacrylate, ethyl methacrylate, propyl methacrylate, ethylmethacrylate, propyl methacrylate, butyl methacrylate, methyl acrylate,ethyl acrylate, propyl acrylate, butyl acrylate and vinyl acetate.

12. A process as claimed in claim 6, wherein said grafting reaction iscarried out in the presence of a non-polymerizable acid selected fromthe group consisting of oxalic acid, formic acid, acetic acid, propionicacid, benzoic acid, sulfuric acid, hydrochloric acid, nitric acid,phosphoric acid and boric acid.

13. A process as claimed in claim 6, wherein said polyethyleneterephthalate is used in the form of yarn, fiber or film.

14. A process as claimed in claim 6, wherein the grafting reaction iscarried out in an inert gas atmosphere.

2. The improvement as claimed in claim 1, wherein said polymerizablemonomer also comprises a polymerizable unsaturated organic acid or itssodium salt.
 3. The improvement as claimed in claim 1, wherein theprocess is carried out by first immersing the polyethylene terephthalatein said halide or a solution thereof to incorporate between about 0.3-25percent of said halide within the polyethylene terephthalate structure,whereafter the grafting reaction in the presence of said monomer isperformed.
 4. The improvement as claimed in claim 1, wherein saidpolymerizable monomer, in addition to said 4-vinyl pyridine, 2-vinylpyridine or 2-methyl-5-vinyl pyridine, contains a member selected fromthe group consisting of acrylic acid, methacrylic acid, maleicanhydride, itaconic acid, vinyl-sulfonic acid, allylsulfonic acid,styrene sulfonic acid and the sodium salts of these organic acids. 5.The improvement as claimed in claim 1, wherein said halide is selectedfrom the group consisting of carbon tetrachloride, carbon tetrabromide,hexachlorOethane and silicon tetrachloride.
 6. A process for the graftpolymerization of polyethylene terephthalate, which comprises immersingthe polyethylene terephthalate in a solution of a halide represented bythe general formula MnX2n 2, wherein M is carbon or silicon, X is Cl orBr and n is 1 or 2, to incorporate between about 0.3-25 percent byweight of said halide into the polyethylene terephthalate structure andthen reacting the halide enriched polyethylene terephthalate with atleast one hydrophilic polymerizable monomer selected from the groupconsisting of 4-vinyl pyridine, 2-vinyl pyridine and 2-methyl-5-vinylpyridine.
 7. A process as claimed in claim 6, wherein said reactionbetween said monomer and said halide enriched polyethylene terephthalateis carried out in a temperature range of from room temperature to 100*C.
 8. A process as claimed in claim 6, wherein said 2 vinyl pyridine,4-vinyl pyridine or 2-methyl-5-vinyl pyridine monomer also contains amember of the group consisting of acrylic acid, methacrylic acid, maleicanhydride, itaconic acid, vinylsulfonic acid, allylsulfonic acid,styrene sulfonic acid and the sodium salt of these organic acids.
 9. Aprocess as claimed in claim 6, wherein said halide is carbontetrachloride, carbon tetrabromide, hexachloroethane or silicontetrachloride.
 10. A process as claimed in claim 6, wherein the graftpolymerization reaction between said monomer and said halide enrichedpolyethylene terephthalate is carried out under irradiation of highenergy ionizing rays.
 11. A process as claimed in claim 6, wherein thegrafting reaction between said polymerizable monomer and said halideenriched polyethylene terephthalate is carried out in the additionalpresence of a vinyl monomer selected from the group consisting ofacrylonitrile, styrene, methyl methacrylate, ethyl methacrylate, propylmethacrylate, ethyl methacrylate, propyl methacrylate, butylmethacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butylacrylate and vinyl acetate.
 12. A process as claimed in claim 6, whereinsaid grafting reaction is carried out in the presence of anon-polymerizable acid selected from the group consisting of oxalicacid, formic acid, acetic acid, propionic acid, benzoic acid, sulfuricacid, hydrochloric acid, nitric acid, phosphoric acid and boric acid.13. A process as claimed in claim 6, wherein said polyethyleneterephthalate is used in the form of yarn, fiber or film.
 14. A processas claimed in claim 6, wherein the grafting reaction is carried out inan inert gas atmosphere.